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Old 11th July 2018, 08:18   #5244  |  Link
MrVideo
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Join Date: May 2007
Location: Wisconsin
Posts: 2,130
Quote:
Originally Posted by Perenista View Post
I assumed that since this sort of modification is possible (while mantaining the contents in lossless) I could easily turn the video 90 degrees clockwise without any unnecessary reencode.
I get the feeling that you do not understand how video works. The video image that is encoded into MPEG-2, H.264 and H.265 (the common codecs that consumers basically use), "scan" from top to bottom, left to right. The aspect ratio is only a "tag" that tells the displaying device how the "pixels" are to be displayed. The decoding of the video is done top to bottom, left to right. Think of the old analog video displays. Same concept, just done with pixels.

The iPad, or any video recording device, does top to bottom, left to right, as if you were holding the recording device landscape. Hence, when you play back your portrait mode video, it looks like you shot it while laying on your side. The only way to "fix" it is to recode it and adding pillar bars on the sides. The vertical resolution is also reduced because the 1920 pixels have to be reduced to 1080 pixels. The horizontal resolution has to be reduced to 607 pixels in order to keep the 9:16 aspect ratio. That is why all these idiots (IMHO) who shoot video with their cell phones result in there being pillar bars of some sort on the left and right. Things are fine if you only view the video on your cell phone, but contribute the video to a TV station and it looks like crap (IMHO). I even harp on my daughter when she sends me vertically shot video.

Sorry, but your video is frack'd.
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